Credit card closure

My credit card was owing something like R5600 so I transferred R6000 into the account. Yesterday I called asking that they close my credit card but they told me I have an outstanding balance. When I asked they said it's Admin fees for the month so I asked if the R400 couldn't cater for the fees. I think I called more than 3 times and they will end up saying we are transferring your call to the team leader then it gets disconnected. To my surprise this morning when I open my App the credit card is no longer showing. I am not sure if it's closed and what happened to the outstanding amount because I didn't pay